#region Copyright & License

//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#endregion

using System;
using log4net.Core;

namespace log4net.Filter {
  /// <summary>
  /// This is a simple filter based on <see cref="Level"/> matching.
  /// </summary>
  /// <remarks>
  /// <para>
  /// The filter admits three options <see cref="LevelMin"/> and <see cref="LevelMax"/>
  /// that determine the range of priorities that are matched, and
  /// <see cref="AcceptOnMatch"/>. If there is a match between the range
  /// of priorities and the <see cref="Level"/> of the <see cref="LoggingEvent"/>, then the 
  /// <see cref="Decide"/> method returns <see cref="FilterDecision.Accept"/> in case the <see cref="AcceptOnMatch"/> 
  /// option value is set to <c>true</c>, if it is <c>false</c>
  /// then <see cref="FilterDecision.Deny"/> is returned. If there is no match, <see cref="FilterDecision.Deny"/> is returned.
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  public class LevelRangeFilter : FilterSkeleton {
    #region Member Variables

    /// <summary>
    /// Flag to indicate the behavior when matching a <see cref="Level"/>
    /// </summary>
    bool m_acceptOnMatch = true;

    /// <summary>
    /// the maximum <see cref="Level"/> value to match
    /// </summary>
    Level m_levelMax;

    /// <summary>
    /// the minimum <see cref="Level"/> value to match
    /// </summary>
    Level m_levelMin;

    #endregion

    #region Constructors

    #endregion

    /// <summary>
    /// <see cref="FilterDecision.Accept"/> when matching <see cref="LevelMin"/> and <see cref="LevelMax"/>
    /// </summary>
    /// <remarks>
    /// <para>
    /// The <see cref="AcceptOnMatch"/> property is a flag that determines
    /// the behavior when a matching <see cref="Level"/> is found. If the
    /// flag is set to true then the filter will <see cref="FilterDecision.Accept"/> the 
    /// logging event, otherwise it will <see cref="FilterDecision.Neutral"/> the event.
    /// </para>
    /// <para>
    /// The default is <c>true</c> i.e. to <see cref="FilterDecision.Accept"/> the event.
    /// </para>
    /// </remarks>
    public bool AcceptOnMatch {
      get { return m_acceptOnMatch; }
      set { m_acceptOnMatch = value; }
    }

    /// <summary>
    /// Set the minimum matched <see cref="Level"/>
    /// </summary>
    /// <remarks>
    /// <para>
    /// The minimum level that this filter will attempt to match against the 
    /// <see cref="LoggingEvent"/> level. If a match is found then
    /// the result depends on the value of <see cref="AcceptOnMatch"/>.
    /// </para>
    /// </remarks>
    public Level LevelMin {
      get { return m_levelMin; }
      set { m_levelMin = value; }
    }

    /// <summary>
    /// Sets the maximum matched <see cref="Level"/>
    /// </summary>
    /// <remarks>
    /// <para>
    /// The maximum level that this filter will attempt to match against the 
    /// <see cref="LoggingEvent"/> level. If a match is found then
    /// the result depends on the value of <see cref="AcceptOnMatch"/>.
    /// </para>
    /// </remarks>
    public Level LevelMax {
      get { return m_levelMax; }
      set { m_levelMax = value; }
    }

    #region Override implementation of FilterSkeleton

    /// <summary>
    /// Check if the event should be logged.
    /// </summary>
    /// <param name="loggingEvent">the logging event to check</param>
    /// <returns>see remarks</returns>
    /// <remarks>
    /// <para>
    /// If the <see cref="Level"/> of the logging event is outside the range
    /// matched by this filter then <see cref="FilterDecision.Deny"/>
    /// is returned. If the <see cref="Level"/> is matched then the value of
    /// <see cref="AcceptOnMatch"/> is checked. If it is true then
    /// <see cref="FilterDecision.Accept"/> is returned, otherwise
    /// <see cref="FilterDecision.Neutral"/> is returned.
    /// </para>
    /// </remarks>
    public override FilterDecision Decide(LoggingEvent loggingEvent) {
      if (loggingEvent == null)
        throw new ArgumentNullException("loggingEvent");

      if (m_levelMin != null)
        if (loggingEvent.Level < m_levelMin) // level of event is less than minimum
          return FilterDecision.Deny;

      if (m_levelMax != null)
        if (loggingEvent.Level > m_levelMax) // level of event is greater than maximum
          return FilterDecision.Deny;

      if (m_acceptOnMatch) // this filter set up to bypass later filters and always return
        // accept if level in range
        return FilterDecision.Accept;
      else // event is ok for this filter; allow later filters to have a look..
        return FilterDecision.Neutral;
    }

    #endregion
  }
}